Voltage regulators



y 1963- T. G. MARSHALL, JR 3,099,790

' VOLTAGE REGULATORS.

Filed March 31, 1958 w v V/A/ .Dc'V/'i Wm j! 1! V/A/ I 65 Viz/7 E510!) F 2* fix 16' INVENTOR.

THmMAs E. MARSHALL, JR

i/TOWWE) United States Patent 3,099,790 VOLTAGE REGULATDRS Thomas G. Marshall, Jn, Franklin Park, N.J., assignor to lltadio Corporation of America, a corporation of Delaware Filed Nlar. 31, 1958, Ser. No. 725,163 11 Claims. (Cl. 323-22) This invention relates to voltage regulating means, and more particularly to voltage regulators for regulating a source of relatively low voltage and for providing a regulated low voltage, high current, low impedance power supply. The voltage regulator circuits of the present invention are particularly useful for regulating the volt-age source available in an automobile so that it may be applied to a portable transiston'zed television receiver, and the like.

The battery in a vehicle, such as an automobile, would usually be receiving a charge while the vehicle is in operation. Changing the speed of the vehicle, for example, usually results in changing the charging rate of the battery. While the voltage regulators supplied with most vehicles are adequate for the purposes originally intended, they do not provide a sufliciently regulated voltage to operate a portable transistorized television receiver satisfactorily.

Accordingly, it is an object of the present invention to provide an improved voltage regulator adapted to regulate a relatively low voltage and to provide a regulated low voltage, high current, low impedance output.

Another object of the present invention is to provide an improved voltage regulator suitable for regulating the voltage supply in a vehicle sufiiciently so that it may be used to power a portable television receiver, and the like, satisfactorily.

A further object of the present invention is to provide an improved voltage regulator employing a transistor whose emitter-collector path is connected in series with an input terminal and an output terminal of the regulator, and whose bias is provided by a constant current device.

Still a further object of the present invention is to provide an improved voltage regulator employing a constant voltage device in addition to the constant current device, permitting the requirements upon both the current and the voltage regulating devices to be relaxed because of this combined regulating action.

In accordance with the present invention, the foregoing and related advantages are attained in a novel volt-age regulator comprising a transistor and a constant current device to bias the transistor. The voltage to be regulated is applied between a pair of input terminals of the voltage regulator circuit. The emitter-collector path of the transistor is connected between one of a pair of input terminals and one of a pair of output terminals. A constant cur rent device, such as a ballast regulator or a lamp having a non-linear resistance, is connected between the base and the collector of the transistor for biasing purposes. The remaining input and output terminals are connected to each other. If low impedance output of the voltage regulator is desired, a resistor of relatively low resistance or a constant voltage device is connected between the base of the transistor and one of the output terminals.

The novel features of the present invention, as well as the invention itself, both as to its organization and methods of operation, will be understood in detail when considered in connection with the accompanying drawing, in which similar reference characters represent similar pants, and in which:

FIG. 1 is a schematic diagram, partly in block diagram form, of an improved voltage regulator, in accordance with the present invention; and

3 ,099,790 Patented July 30, 1963 FIG. 2 is a schematic diagram of a modification of the improved voltage regulator.

Referring now to FIG. 1, there is shown an improved voltage regulator 10 having a positive input terminal 12 and a negative input terminal 14. A voltage V to be regulated is applied across the input terminals 12 and '14. The voltage regulator 10 has a positive output terminal 16 and a negative output terminal 18 for applying a load 19 therebetween, whereby to receive a regulated voltage out- A transistor 20, shown here as a PNP transistor, has an emitter connected to the negative output terminal 18, and a collector connected to the negative input terminal 14. A constant current device 22 is used to bias the transistor 20. The constant cur-rent device may comprise a non-linear resistance having a positive voltage coefficient of resistance, such as a ballast regulator or an ordinary lamp. It will be understood that, by the term constant current device, as used herein and in the appended claims, is meant an impedance through which the current variations are relatively smaller than the voltage variations across the device. A lamp, for example, whose resistance varies directly with the voltage across it, is such a nonlinear impedance as may be considered a constant current device within the scope of the instant invention, since the current through the lamp will remain substantially constant over a relatively wide range of voltages impressed across the lamp.

The operation of the voltage regulator 10, thus far described in FIG. 1, will now be explained. Let it be assumed that the voltage V to be regulated has a tendency to increase. This increase in voltage will tend to increase the current through the load 19. It is a well-known fact, however, that the current flowing through the emitter of a transistor is equal to I =kl where I is the current through the emitter, I is the current through the base, and k is the emitter to base current gain of the transistor.

Since the current through the base is maintained constant by the constant current device 22, the current through the load 19, between the output terminals 16 and 18, will 'alsoremain constant. The voltage across the load 19 will, therefore, remainsubstantially constant. It will be understood, also, that a tendency for the unregulated voltage V to decrease will not affect the substantially constant emitter current, and the voltage across the load 19 will remain substantially constant.

If it is desired to have a low output impedance voltage regulator, making the output voltage V independent of any changes in the impedance of the load 19, an impedance 24, such as a resistor, is connected between the base of the transistor 20 and the positive output terminal 16. Looking back from the output terminals 16 and 18, an effective impedance appears equal to impedance 24 divided by the currentg-ain, k, of the transistor 20. This effective impedance may be made low with respect to the impedance of the load 19 without causing an excessive current flow compared to the load current by virtue of the fact that the actual impedance 24 is k times the impedance that is reflected to the output terminals 16 and 18.

Referring, now, to FIG. 2, there is shown a voltage regulator 30, in accordance with the present invention, wherein the constant current device comprises a lamp 32 connected between the base and the collector of the transistor 20. An impedance having a constant voltage characteristic, such as a zener diode 34, has its anode connected between the base of the transistor 20 and its cathode connected to the positive output terminal 16.

The operation of the voltage regulator 30 of FIG. 2 will now be explained. If the constant current device 32 is an imperfect device, such as a GE40 or GE47 bulb, in that some current variations will occur for variations in the unregulated input voltage V then a voltage variation will occur between the base of the transistor 20 and the output terminal 16 if the diode 34 were omitted. This voltage variation would also be across the load 19. This voltage variation, although smaller than would be the case if element 32 were a linear resistor, may be too high for certain applications. With the zener diode 34 connected as shown in FIG. 2, the voltage across its terminals, and hence the output, will remain essentially constant. It should be noted that the use of the constant voltage device 34 has relaxed the requirements upon the constant current device, lamp 32, for a given amount of regulation. It should also be noted that the constant current device 32 will reduce the variations in the current in the constant voltage device, diode 34, thereby relaxing the requirements upon the latter device. Thus, the two devices, lamp 32 and diode 34, cooperate to give better regulation against changes in input voltage than would obtain with either device used by itself.

The constant voltage device, diode 34, has a very low dynamic impedance and hence a low dynamic impedance is reflected across the output terminals making the output voltage independent of changes in the impedance of the load 19.

While a PNP transistor has been described and illustrated in the circuits of the present invention, it will be understood that an NPN transistor may be used if the polarities of the terminals and the zener diode are reversed.

What is claimed is:

1. A regulating circuit for a source of unidirectional unregulated voltage comprising a transistor having an emitter, a base, and a collector, a pair of input terminals between which said unregulated voltage can be applied, a pair of output terminals for deriving a regulated unidirectional voltage therebetween, means connecting the emitter-collector path of said transistor between one of said input terminals and one of said output terminals, means connecting. the other of said input terminals to the other of said output terminals, a constant current device having two terminals only, and means connecting said constant current device directly between said base and said collector.

2. A regulating circuit for a source of unidirectional unregulated voltage comprising a transistor having an emitter, a base, and a collector, a pair of input terminals between which said unregulated voltage can be applied, a pair of output terminals for deriving a regulated unidirectional voltage therebetween, means connecting the emitter-collector path of said transistor between one of said input terminals and one of said output terminals, means connecting the other of said input terminals to the other of said output tenrninals, a constant current device having two terminals only, means connecting said constant current device only between said base and said collector, an impedance, and means connecting said impedance between said base and said other of said output terminals.

3. A regulating circuit for a source of unidirectional unregulated voltage comprising a transistor having an emitter, a base, and a collector, a pair of input terminals between which said unregulated voltage can be applied, a pair of output terminals for deriving a regulated unidirectional voltage therebetween, means connecting the emitter-collector path of said transistor between one of said input terminals and one of said output terminals, means connecting the other of said input terminals to the other of said output terminals, a non-linear constant current impedance device, and means connecting said device only between said base and said collector.

4. A regulating circuit for a source of unidirectional unregulated voltage comprising a transistor having an emitter, a base, and a collector, 'a pair of input terminals between which said unregulated voltage can be applied, a pair of output terminals for deriving a regulated unidirectional voltage therebetween, means connecting the emitter-collector path of said transistor between one of said input terminals and one of said output terminals, means connecting the other of said input terminals to the other of said output terminals, a non-linear constant current impedance device having two terminals only, means connecting said device only between said base and said collector, and voltage dropping means connected between said base and said other of said input terminals.

5. In a regulating circuit of the type wherein a source of unidirectional voltage to be regulated is applied to a pair of input terminals, and wherein a load is supplied with a regulated unidirectional output voltage between a pair of output terminals, a transistor having an emitter, a base, and a collector, means connecting the emitter-collector path of said transistor between one of said input terminals and one of said output terminals, means connecting the other of said input terminals and the other of said output terminals to each other, a constant current device having two terminals only, means connecting said constant current device directly between said base and said collector, an impedance, and means connecting said im pedance between said base and said other of said output terminals.

6. In a regulating circuit of the type wherein a source of unidirectional voltage to be regulated is applied to a pair of input terminals, and wherein a load is supplied with a regulated unidirectional output voltage between a pair of output terminals, a transistor having an emitter, a base, and a collector, means connecting the emitter-collector path of said transistor between one of said input terminals and one of said output terminals, means connecting the other of said input terminals and the other of said output terminals to each other, a constant current device having two terminals only, means connecting said constant current device only between said base and said collector, voltage dropping means, and means connecting said voltage dropping means between said base and said other of said output terminals.

7. In a regulating circuit of the type wherein a source of unidirectional voltage to be regulated is applied to a pair of input terminals, and wherein a load is supplied with a regulated unidirectional output voltage between a pair of output terminals, a transistor having an emitter, a base, and a collector, means connecting the emitter-collector path of said transistor directly between one of said input terminals and one of said output terminals, means connecting the other of said input terminals and the other of said output terminals directly to each other, a constant current device having two terminals only, means connecting said constant current device directly between said base and said collector, a resistor, and means connecting said resistor between said base and said other of said output terminals, said resistor having an elfective impedance that is relatively smaller than said load.

8. A voltage regulating circuit having a pair of input terminals between which a source of voltage to be regulated can be applied, a pair of output terminals for receiving a load therebetween to apply a regulated voltage thereto, a transistor having an emitter, a base, and a collector, a non-linear impedance having a positive voltage ooeflicient of resistance, means connecting said impedance only between said base and said collector, a constant voltage device, means connecting said constant voltage device between said base and one of said output terminals, means connecting one of said input terminals with said one of said output terminals, and means connecting the emittercollector path of said transistor between the other of said input terminals and the other of said output terminals.

9. A voltage regulating circuit having a pair of input terminals between which a source of voltage to be regu lated can be applied, a pair of output terminals for receiving a load therebetween to apply a regulated voltage thereto, a transistor having an emitter, a base, and a collector, a lamp, means connecting said lamp between said base and said collector, a constant voltage device, means connecting said constant voltage device between said base and one of said output terminals, means connecting one of said input terminals with said one of said output terminals, and means connecting the emitter-collector path of said transistor between the other of said input terminals and the other of said output terminals.

10. A voltage regulating circuit having positive and negative input terminals between which a source of voltage to be regulated can be applied, positive and negative output terminals for receiving a load therebetween to apply a regulated voltage thereto, a transistor having an emitter, a base, and a collector, a lamp, means connecting said lamp between said base and said collector, a diode, means connecting said diode between said base and said positive output terminal, means connecting said positive input terminal with said positive output terminal, and means connecting the emitter-collector path of said transistor between said negative input terminal and said negative output terminal.

11. A voltage regulating circuit having positive and negative input terminals between which a source of voltage to be regulated can be applied, positive and negative output terminals for receiving a load therebetween to apply a regulated voltage thereto, a transistor having an emitter, a base, and a collector, a lamp, means connecting said lamp between said base and said collector, a diode having an anode and a cathode, means connecting said anode to said base and said cathode to said positive output terminal, means connecting said positive input terminal with said positive output terminal, and means conmeeting the emitter-collector path of said transistor between said negative input terminal and said negative output terminals.

References Cited in the file of this patent UNITED STATES PATENTS 2,576,100 Brown Nov. 27, 1951 2,647,958 Barney Aug. 4, 1953 2,698,416 Sherr Dec. 28, 1954 2,897,430 Te Winkel July 28, 1959 2,920,265 Siedband Jan. 5, 1960 FOREIGN PATENTS 1,129,336 France Sept. 3, 1956 

1. A REGUALTING CIRCUIT FOR A SOURCE OF UNIDIRECTIONAL UNREGULATED VOLTAGE COMPRISING A TRANSISTOR HAVING AN EMMITER, A BASE, AND A COLLECTOR, A PAIR OF INPUT TERMINALS BETWEEN WHICH SAID UNREGULATED VOLTAGE CAN BE APPLIED A PAIR OF OUTPUT TERMINALS FOR DERIVING A REGULATED UNIDIRECTIONAL VOLTAGE THEREBETWEEN, MEANS CONNECTING THE EMMITER-COLLECTOR PATH OF SAID TRANSISTOR BETWEEN ONE OF SAID INPUT TERMINALS AND ONE OF SAID OUTPUT TERMINALS MEANS CONNECTING THE OTHER OF SAID INPUT TERMINALS, TO THE OTHER OF SAID OUTPUT TERMINALS, A CONSTANT CURRENT DEVICE HAVING TWO TERMINALS ONLY, AND MEANS CONNECTING SAID CONSTANT CURRENT DEVICE DIRECTLY BETWEEN SAID BASE AND SAID COLLECTOR. 